Environmental Controls on Aquatic Ecosystem Sensitivity to Metal Bioaccumulation

金属在环境中自然存在；然而，人类活动改变了这些元素的生物地球化学循环，增加了它们向空气、土壤和水中的释放。点源排放的金属污染可对生态系统和人类健康产生局部和长期影响（通过大气运输）。目前关于环境条件如何控制沉积在加拿大北部的金属的命运的信息不足。我的研究项目最近的证据表明，与温带地区的湖泊相比，北极湖泊对金属生物积累（特别是汞）更敏感。为了评估和减轻金属污染对这些巨大水资源的影响，需要新的研究来确定气候相关因素如何影响金属的生物积累及其在食物链中的转移。所涉及的环境过程是复杂的，发生在多个尺度上。在生态系统尺度上，高纬度地区的非生产性湖泊（即有机质产量较低）可能在食物链的底部积聚更多的金属，因为从水中吸收的污染物“集中”在较少的微生物生物量中。在生物尺度上，较冷的温度和较低的食物供应改变了消费者的生理机能，可能会提高他们的金属含量。特别是，较慢的生长速度可能导致北极水生生物中较高的金属含量。在接下来的五年里，该研究项目将重点关注两个关键的气候相关因素——温度和生产力——在控制北方水生生态系统对汞和砷的生物积累和食物链转移的敏感性方面的作用。由于其在大气中的长距离迁移，汞是一种重要的污染物，尽管北方资源开发释放了砷，但关于北极湖泊中砷积累的信息很少。实验室和实地实验将调查寒冷、非生产性环境如何促进金属的生物积累及其通过食物链的转移。由于这些因素在环境中是相互关联的，因此需要在受控条件下的实验方法来分离潜在的独立效应和交互效应。该研究项目将为未来气候变化对金属污染的影响提供基于过程的预测，提高我们确定金属沉积命运的能力，并支持管理和保护北方人仍广泛用于自给渔业的大量水资源。

Metals occur naturally in the environment; however, human activities have altered the biogeochemical cycles of these elements and increased their release to air, soils, and water. Metal pollution from point source emissions can have both local and long-range impacts (through atmospheric transport) on ecosystem and human health. There is currently insufficient information on how environmental conditions control the fate of metals deposited in Canada's North. Recent evidence from my research program indicates that Arctic lakes are more sensitive to metal bioaccumulation (specifically mercury) compared with lakes at temperate latitudes. New research is needed to identify how climate related factors affect the bioaccumulation of metals and their transfer in food chains in order to evaluate and mitigate impacts of metal pollution on these vast water resources. The environmental processes involved are complex and occur at multiple scales. At the ecosystem scale, unproductive lakes (i.e. having lower organic matter production) at higher latitudes may accumulate more metals at the base of the food chain because the contaminant mass taken up from water is “concentrated” in less microbial biomass. At the organism scale, colder temperatures and low food availability alter the physiology of consumers that may enhance their metal levels. In particular, slower growth rates may lead to higher metal levels in Arctic aquatic organisms. Over the next five years, this research program will focus on the role of two key climate-related factors - temperature and productivity - in controlling the sensitivity of northern aquatic ecosystems to bioaccumulation and food chain transfer of mercury and arsenic. Mercury is a priority contaminant due to its long-range atmospheric transport, and little information is available on arsenic accumulation in Arctic lakes despite releases from northern resource developments. Laboratory and field experiments will investigate how cold, unproductive environments enhance organism accumulation of metals and their transfer through the food chain. Because these factors are correlated in the environment, experimental approaches under controlled conditions are needed to separate potential independent and interactive effects. This research program will provide process-based predictions for future climate-change impacts on metal pollution, improve our ability to determine the fate of metal deposition, and support the management and protection of vast water resources still widely used by northerners for subsistence fisheries.